Photosensitive benzocyclobutene for stress-buffer and passivation applications (one mask manufacturing process)

Photosensitive benzocyclobutene (Photo-BCB) has been widely reported on for use as a dielectric material in multilayer packaging applications, including: MCMs, IO redistribution, and flat panel display. Photo-BCB has many properties which are highly attractive for these applications, including: a simple processing scheme which is compatible with existing IC manufacturing techniques, low level of ionics, low moisture uptake, low cure temperatures, rapid thermal curing, high optical transparency, high planarization level, high thermal stability, high solvent resistance, very low outgassing, and a low dielectric constant. Photo-BCB is also being actively evaluated for wafer-level applications such as stress-buffer and passivation. In this paper, we discuss the Photo-BCB properties and processing steps as they relate to these two applications. We also compare the manufacturing scheme based on a one mask process for memory die, to the steps in a two mask process for stress-buffer and passivation.